Jordan

The problem is that for some reason the config section can't be found in .net framework configuration files.

There are few things that can cause the problem.
1. The AppPool under which the site is running is not .NET 4. In that case change the Framework version of the Application Pool to v4.0.
2. You have nested application with .NET 2. (Only if you make changes with the default configuration of TeamPulse in IIS)

If the above not fix it you can try to add on the top of the web.config:

The reason this section exists is to enable integration scenarios. The authentication service allows you to get an authentication cookie from our app without relying on your web browser. The cookie is required when making requests to our data service or any other service that cannot be accessed anonymously. If you don't need to integrate with TeamPulse in this way, it should be safe to leave this section commented out.

After this issue was resolved another unrelated error occurred that was caused by a section of the web.config being locked by the global IIS configuration. The error was the following:

"This configuration section cannot be used at this path. This happens when the section is locked at a parent level. Locking is either by default (overrideModeDefault="Deny"), or set explicitly by a location tag with overrideMode="Deny" or the legacy allowOverride="false"."
Config Source

149: <system.webServer>

150: <httpErrors errorMode="Detailed"/>

151: <modules runAllManagedModulesForAllRequests="true">

This error was resolved by unlocking the httpErrors section in the global IIS configuration as illustrated in this blog post.

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